The Very End
by CaffeineChaos243
Summary: Inspired by a tumblr prompt: Castiel has turned bad. It ends in a battle after months of effort on the Winchesters part, effort to save him. He kills Sam. Dean's only job was to protect his younger brother. and he failed. After another battle, Dean kills Cas. Dean is left broken and alone, thinking he has no one in the world. It's revealed that isn't the case at all.
1. The End

Dean sat in the Impala, parked along the side of backroad in Nebraska. The morning sun was barely peaking above the horizon behind him and the car was chilly, but he didn't notice. He'd been numb for days now. He cleaned the gun on his lap with steady hands and a resting frown.

It had been exactly six months since Castiel had….turned. He remembered the panic that gripped his chest when Sam burst through the door of the Bunker. Those three words still echoed in his head. "Dean, it's Cas."

They spent months searching for a cure or a spell or _someone_ that could help. They tried to find an answer. What happened? Why? Dean had dropped to his knees in his room and begged Chuck to return. To just listen. But no help came. No answer was found. Castiel continued his killing and torturing and slowly eradicated everyone the brothers knew.

When it came time to confront him, Dean felt ready. Their plan was definitely not fool proof but it was the best they had. If it worked on Lucifer….it could work on whatever the hell Cas was now. Right? They could get their friend back.

No. Dean's hands trembled as he reached for a polishing cloth. Three days. It had been three days since Sam had knelt before him, telling him to get up and that they would be okay. Dean's jaw still hurt every time he moved it, thanks to the backhanded blow from Cas. The image of Sam's bloodied face in front of him, urging him to keep going, turned to the bloodied gasp of pain as a knife was ripped across Sam's throat from behind.

The shock of the hot blood soaking Dean's front mixed with the limp body in his arms was too much. He had stared dumbly as Cas smirked down at them, the knife still in his hand. Dean couldn't even remember what Cas had said before he had disappeared. The tormented sound Dean had made as he scooped his bigger, younger brother into his arms was not one any person should have to make.

Dean burned Sam's body in the field where they had burned Mary's. And Garth's. Claire. Jody. And all of the hunters and friends the brothers had known along the way. The lines of crosses covered too much of the field.

Dean stared out the window as the sun rose into the sky. The clouds were pinks and oranges. He was thankful for none of the dark reds or blues or purples. None of the colors of blood, bruises, or pain. A figure shifted in the passenger seat beside him but he didn't turn to them. He knew Cas was dead. It wasn't actually him.

The memory of gushing blood and burning light slammed back into Dean's mind. He couldn't forget the pain in his chest as the angel burned out of the vessel and disappeared, gone from the meat suit he had used and abused for so long. Dean had burned Cas's body in the same meadow, because even though Cas had murdered everyone else, he was still family.

With a long, slow breath, Dean lifted his cleaned gun. He stared at it, not remembering where it had come from. Was this one from Sam? Or from some pawn shop in some small forgotten town? Some of the empty alcohol bottles rattled under his seat as he shifted.

"I'm sorry Sam." He said out loud, breaking the stillness of the morning. His mouth was dry and his voice cracked when he said his brother's name. He hadn't spoken in days. "I failed you and I'm sorry." His eyes burned with tears that quickly began leaking down his cheeks. "I love you, Sammy." He whispered.

"Just get on with it already." Castiel said in the passenger seat. Dean ignored him. _He isn't real. I killed him._ His heart lurched as his breathing hitched with a sob.

"Cas…." He whispered as he rested the handgun against the steering wheel and hung his head. Everything was so heavy. "I couldn't save you."

"Do it." Castiel said beside him, his voice dripping with anticipation.

"I'm sorry." Dean said through the lump in his throat and tears in his eyes. He lifted his head and struggled to bring the gun to his mouth. It was so hard, like every force was pushing against his arm. He used his other as support until the barrel rested against his lips.

"I love you, Cas." He said in a steady voice before the cold metal touched the roof of his mouth and he pulled the trigger.


	2. This Shouldn't Be The End

Cas sat frozen in the passenger seat of the Impala. He stared wide eyed at the gore-painted interior and the still body of the man beside him. His hands still grasped Dean's arms, though his struggle to keep the gun from reaching Dean's mouth had been futile. He let go of the now limp arm and it fell heavily onto Dean's chest.

He sat back against the door with a defeated sigh. His chest twinged where Dean had plunged the knife a day ago. As he stared at the rising sun through the back window, his shock turned to hatred. Hatred for that damned parasite.

They didn't know _anything_ about it. Nobody in heaven or hell or on earth knew where it came from. Once it had latched itself onto Dean's brain, Cas had panicked. He tried blasting it away, they tried casting spell after spell, and they even tried piercing it with the demon blade. Nothing worked.

The first few days it was okay. Dean mentioned a headache but brushed it off quickly. Cas knew though. He could sense Dean's growing fear, the panic. He knew something was seriously wrong. Dean became jumpy around them and kept mumbling about doing research.

It wasn't until the fourth morning that Dean changed. The parasite took over and suddenly, everyone was an enemy in Dean's eyes. For some reason, Dean targeted Cas the most viciously. After locking Dean in the Bunker dungeon and tending to their wounds, Sam and Cas threw themselves into research. Maybe they had missed something?

Dean's scream of anguish and the force of the internal pain he was feeling hit Cas like a house on the fifth day. He struggled from his knees as Sam sprinted through the room towards the basement. Towards his brother.

They burst through the door to find Dean sobbing on the floor. Sam tried to talk to him, tried to get through. Dean kept whimpering Sam's name but wouldn't focus on his brother. Sam looked to Cas for help, for an idea. Anything. Cas stared back blankly. He was out of ideas.

On the sixth day, Cas entered the dungeon room with a small pie and several other foods, hoping Dean would eat. Dean stood against the far wall of the dungeon. His fists were clenched and his breath ragged. His normally bright eyes were bloodshot and dark. So vastly different than the demon eyes he had once worn. This was more frightening. Cas offered the pie seconds before Dean attacked.

Cas remembered every detail of the fight. Dean kept talking about people being dead and how he had failed and it couldn't continue. Cas should have called for Sam. He should have just teleported out. Instead he thought maybe he could reason with Dean. It wasn't until the knife appeared from nowhere and plunged deeply into Cas's chest that he realized how far gone Dean had become. Dean had lifted his head to face Cas, inches away.

"You didn't have to kill him." He whispered in a broken voice." I shouldn't have had to do this. I don't want to." Cas gasped as Dean twisted the knife and muttered something in Enochian that didn't make sense. Dean let go, his eyes full of tears, as he slowly backed from the room.

Sam burst into the room in panic, which only grew as he found Cas sitting on the floor, having sunk to the ground with his back against the wall and the knife still grating between his ribs. He hadn't even thought to heal himself.

It was the seventh day, this day, that Castiel had found him again. He should have followed Dean from the start. He realized that now. He looked over at the broken man in the driver's seat. The gunshot had torn through the parasite. It was dead. Now they knew how to kill it.

"I have failed you, Dean." Cas said in a gravelly voice. He had tried everything to talk Dean down. It had been useless. Dean was dead.

Cas let his head fall into his hands. He could bring Dean back. He could. He thought about the past few years and how hard and withdrawn the Winchesters had become. They saved the world, repeatedly, but at such a high cost to their minds and souls. Cas tried to heal them when he could, but Dean had stopped letting Cas touch him. Had walled himself off from everyone. He couldn't put Dean through all of that again. He just couldn't.

Cas got out of the impala as he dialed Sam's cellular phone number. He told Sam their location as he walked into the field beside the parked car and began building a funeral pyre. He tried to ignore the keening from the roadside once Sam arrived.

As Cas finished the pyre, Sam's large hand appeared on his shoulder. "Will….will you get the others?" Sam asked, his voice and spirit broken. Cas nodded and disappeared.

It took twenty minutes to collect all of the people that cared about Dean Winchester. Cas's eyes were the only dry ones as he opened the driver's door of the Impala and Sam stooped to pick up his brother. They walked as a group to the pyre. He couldn't understand why he couldn't cry. He surely felt a deeper sense of pain than some of the humans here.

Jody stepped forward and said some words, but Cas wasn't focused. He watched as various people stepped forward, some with smiles, most with tears. It wasn't until Sam muttered a prayer that Cas's focus snapped back into place. He turned to Sam, who was kneeling with his back to everyone and struggling to light the fire.

Cas walked up and took the matches from Sam's trembling hands. He grasped Sam's arm briefly before Sam staggered away to lean on Jody who was sobbing loudly. Cas smoothly lit the matchbook and tossed it under the pyre.

Castiel, Angel of the Lord, Honorary Winchester, brother, friend, Man of letters, and so much more, watched as the flames flickered around the blanket wrapped body. He was all of those things because of Dean Winchester. He wouldn't let the man's legacy die because of some…. _worm_. He clenched his fists as he stared at the smoke that curled and undulated into the sky. He would eradicate the parasite and whoever created it. Warm tears rolled down his cheeks as the fire heated his face and Dean Winchester's body burned.


	3. MOVED TO A03

Hey all. If you've read up to this point THANK YOU! Truly, I adore you.

However, I abhor this site. The file manager is so frustrating and I don't know how to reply directly to reviews and I just don't like it. I have everything, and more, on AO3 and I urge you to follow me over there. I love hearing from you and Ao3 is so much easier. Let me know if you follow me there and please review!

/users/Caffeine_Chaos243


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